TOPIC:

I have a setup with 2 full range speakers (Focal 906) (L&R) driven from one amp via XLR inputs, 2 mid bass speakers (ceiling mounted subs) (L&R) driven from another amp via XLR inputs and a powered Rythmik sub for very low end (can use balanced or unbalanced inputs.)

Can I use the 4 XLR outputs to drive L&R channels for both full range and mid bass, and then use one or two of the unbalanced outs to drive the Rythmik subwoofer?

I want to use the SHD as both an active crossover for all 5 speakers, plus utilize Dirac to optimize output to all 5 speakers independently.

The SHD will sit behind the DAC and preamp and before the amplifiers.

Finally, can the volume control be bypassed?

Thanks

The SHD has 4 independent output channels. You can simultaneously use XLR and RCA outputs but they are paired so that XLR output 1 and RCA output 1 will be sent the same signal etc.

So no, an SHD can't do what you want.

Thanks for the response.

Would the DDRC-88A be the correct product for this application then? I want to apply DSP correction to every speaker independently - 5 speakers in total.

What frequency range are you sending to your ceiling speakers? My gut feeling on how best to improve your system would be to stop using these completely and them use an SHD to optimally integrate your main speakers and sub.

I've got those ceiling subs limited to 100hz with crossovers. Simplifying the system might be a good place to start. I would have less invested in an SHD than the additional amp and DDRC88a needed in order to run them all independently.

What about the digital coax outs? Can they be used in tandem with the 4 XLR outs? I could run the subwoofer from an external DAC on one of the digital outs. Would Dirac recognize this output as we as the 4 analog outs for 5 separate output channels?

Dirac only deals with a left and right channel, not the separate outputs of the SHD.

The SHD has 4 channels, all outputs can only come from these 4 channels.

Sounds like the DDRC-88A is going to be the only unit that can provide Dirac DSP on more than 4 channels. I just have to get over my apprehension about the 48khz sample rate.

How big is your room? I'm still not convinced you need the ceiling subwoofer at all and if you just relied on your Rhythmik sub you wouldn't need the extra channels of a DDRC 88A.

Well the Focal mains may be full range but they are quite small so I can well believe that subs are needed even in a small room.

I'm sure DDRC-88A is a fine unit, I've never used one but from what I remember of the specs it just isn't as good as an SHD.

I would provocatively say that you don't need 5 channels, 3 or 4 would do. What you do need is 5 outputs and the SHD can normally manage that. As a simple example, both my SHD systems are 2.1, i.e. 3 channels, but only using 2 SHD channels to provide 3 outputs. I provide exactly the same full range signal to my mains and sub, tweak the sub LPF, balance them slightly bass heavy by ear and then let Dirac integrate them to a flat response.

With 2 mains and 3 subs you have at least two way of sharing four SHD channels.
A. Channels 1 and 2 to the mains and ceiling subs, channel 3 to the low sub.
B. Channels 1 and 2 to the mains, channels 3 and 4 to the ceiling subs and low subs.

Now some purists would say that can't possibly work, and surely it wouldn't stand a hope withut Dirac and a bit of luck from how your speakers integrate naturally. I'm quite capable of designing crossovers, examining drive units specs and all that tech stuff. But I'm old and lazy and I'm not going to do the complicated thing if the simple thing works well. For me the simple thing worked very well, on two separate 2.1 SHD systems. It sounds brilliant.

So that's another option you have, use a high quality SHD and share 4 SHD channels between 5 outputs. You have to ask yourself whether you really need 5 channels of crossovers on a lower quality box or not. Maybe you don't need what you think you need. I don't use any crossovers at all.

Unfortunately I've realised you possibly need 5 channels of delays for proper time alignment between speakers.. If some speakers you share SHD channels of happen to naturally be time aligned that isn't a problem, otherwise you may have to add external delays on some channels.

entripy wrote:

Well the Focal mains may be full range but they are quite small so I can well believe that subs are needed even in a small room.

Absolutely. It's the use of the two subs in the ceiling in addition to the larger Rhythmik sub that I was questioning.

Well, here's my setup to clarify the scenario:

Room is 24' x 30' with 11' ceilings and opens to multiple rooms and halls. Focal 906's in fixed positions on shelves. Ceiling subs are OEM SYSTEMS ENC-816LP AND SE-80SWF, Rythmik E15 in fixed position under a lamp table. Listening position is the left most seating area on the couch.
Focal 906's are driven with a Purifi ET1400 amp, "400 wpc"
Ceiling subs driven with an Emotiva 100wpc amp
Rythmik E15 is self powered and connected via REL HT-Air Wireless connector.



Physical movement of any of the components is restricted with the exception of the subwoofer, but alternate placement clear across the room to the left in an alcove behind another sofa (which is not in the picture.)

Ceiling subs were added to give more "weight and body" to the severely restricted Focal 906's. Everything in the room is compromised as far as physical location.

I suspect the time alignment of the mains and ceiling subs will be very similar (no doubt by design) so they could probably share the same Left and Right SHD channels, if you have low pass filters for the ceiling subs you can tune that may help integration.

The Rythmik sub will then need delaying most on a 3rd SHD channel with a mix of Left and Right.

You then have the option of using crossovers between the Rhythmik sub and the combined mains and ceiling subs. What you can't do is use crossovers between the mains and ceiling subs which is why a low pass filter on the latter may be useful.

With multiple speakers time alignment is the first thing you need to do, typically using REW to derive accurate delay times.

Then when the SHD plugin is set up with correct delays on each channel Dirac can be used to obtain an overall flat frequency response. Remember that Dirac on SHD is two channel, simple Left and Right, and it does not know or care how many speakers you use.

I would certainly be tempted to try this approach with an SHD rather than another device with more channels. And you still have a fourth SHD channel left to squeeze another sub in

I've crossed over the ceiling subs with 100mhz/8 ohm/12db rolloff crossovers (even though the subs are listed as 4ohm nominal.) from Parts Express, so I do have the ceiling subs limited, but not the Focal's.

I've definitely done some experimenting with REW and a Umik-1, with filters placed in Roon's convolver option. It made a significant impact.

I didn't continue the path of refining the REW filters, thinking there was probably a better way to control every speaker independently via miniDSP component, and that Dirac would probably be easier to master than REW. Ultrasonic's advice to forgo the ceiling subs and entripy's advice to combine Focal and ceiling subs together (with the existing crossover) are two diverse paths that I should probably explore to seek the best outcome - both equally valid.